Well, I went ahead and got the part thru my local Ford Parts dealer ($48.44 w/ tax) and they had no trouble locating the part and actually had 2 in stock... I guess they know the high failure rate on this part!
Anyway, got it installed and everything is working fine now.
Here's the old part...
Heater "Y" Pipe
Outlet to ByPass Tube rusted thru and "Y" seam damage
Closeup on "Y" seam damage, metal was too weak for repairs
This failure had been going on for a while... but the funny thing is that I never saw the Temp Gauge go past the middle, where it always sits at normal operating temp. I never had a chime or a low coolant warning on the dash, never saw a leak, puddle or stain in the engine bay area. And I never smelled coolant untill a week ago when I started using the heater. Then yesterday I pop the hood to have a look since the heater stopped working and it sounded like a tea kettle, steam but no coolant gushing and just a faint stain around the PS Pump, engine and firewall.
I had to add 2 gallons of 50/50 to bring it up to normal level, but there were no signs of trouble, unless this hole just happened when I stated using the heater last week!
I had a hard time finding the specified coolant to use on my 2000 Windstar and the Ford dealer wanted too much for one bottle, so I got a bottle of Peak "All Green" Antifreeze which states it's compatible with "Ford 2000 and earlier" models.
Anyway I need to do a flush soon as the old coolant is obviously contaminated with rust... I just hope the bypass tube holds, I don't want to mess with the intake all over again!